Proceedings Article | 3 March 2010
Proc. SPIE. 7625, Medical Imaging 2010: Visualization, Image-Guided Procedures, and Modeling
KEYWORDS: Endoscopy, Neck, Imaging systems, Cameras, Calibration, Video, Image registration, Endoscopes, Head, Optical tracking
Methods for accurate registration and fusion of intraoperative cone-beam CT (CBCT) with endoscopic video have been
developed and integrated into a system for surgical guidance that accounts for intraoperative anatomical deformation and
tissue excision. The system is based on a prototype mobile C-Arm for intraoperative CBCT that provides low-dose 3D
image updates on demand with sub-mm spatial resolution and soft-tissue visibility, and also incorporates subsystems for
real-time tracking and navigation, video endoscopy, deformable image registration of preoperative images and surgical
plans, and 3D visualization software. The position and pose of the endoscope are geometrically registered to 3D CBCT
images by way of real-time optical tracking (NDI Polaris) for rigid endoscopes (e.g., head and neck surgery), and
electromagnetic tracking (NDI Aurora) for flexible endoscopes (e.g., bronchoscopes, colonoscopes). The intrinsic (focal
length, principal point, non-linear distortion) and extrinsic (translation, rotation) parameters of the endoscopic camera
are calibrated from images of a planar calibration checkerboard (2.5×2.5 mm2 squares) obtained at different
perspectives. Video-CBCT registration enables a variety of 3D visualization options (e.g., oblique CBCT slices at the
endoscope tip, augmentation of video with CBCT images and planning data, virtual reality representations of CBCT
[surface renderings]), which can reveal anatomical structures not directly visible in the endoscopic view - e.g., critical
structures obscured by blood or behind the visible anatomical surface. Video-CBCT fusion is evaluated in pre-clinical
sinus and skull base surgical experiments, and is currently being incorporated into an ongoing prospective clinical trial in
CBCT-guided head and neck surgery.
